dev

Author: davidhassell

cf/cfdatetime.py

@@ -1,7 +1,6 @@
 import datetime
 from functools import partial
 
-import cftime
 import numpy as np
 
 from .functions import _DEPRECATION_ERROR_CLASS
@@ -10,17 +9,10 @@
 default_calendar = "gregorian"
 
 # --------------------------------------------------------------------
-# Mapping of CF calendars to cftime date-time objects
+# Mapping of CF calendars to cftime date-time objects (that gets
+# populated in the `dt` function).
 # --------------------------------------------------------------------
-_datetime_object = {
-    ("",): partial(cftime.datetime, calendar=""),
-    (None, "gregorian", "standard", "none"): cftime.DatetimeGregorian,
-    ("proleptic_gregorian",): cftime.DatetimeProlepticGregorian,
-    ("360_day",): cftime.Datetime360Day,
-    ("noleap", "365_day"): cftime.DatetimeNoLeap,
-    ("all_leap", "366_day"): cftime.DatetimeAllLeap,
-    ("julian",): cftime.DatetimeJulian,
-}
+_datetime_object = {}
 
 canonical_calendar = {
     None: "standard",
@@ -40,7 +32,7 @@
 _calendar_map = {None: "gregorian"}
 
 
-class Datetime(cftime.datetime):
+class Datetime:
     """A date-time object which supports CF calendars.
 
     Deprecated at version 3.0.0. Use function 'cf.dt' to create date-
@@ -134,6 +126,26 @@ def dt(
     (2003, 4, 5, 12, 30, 15)
 
     """
+    import cftime
+
+    if not _datetime_object:
+        _datetime_object.update(
+            {
+                ("",): partial(cftime.datetime, calendar=""),
+                (
+                    None,
+                    "gregorian",
+                    "standard",
+                    "none",
+                ): cftime.DatetimeGregorian,
+                ("proleptic_gregorian",): cftime.DatetimeProlepticGregorian,
+                ("360_day",): cftime.Datetime360Day,
+                ("noleap", "365_day"): cftime.DatetimeNoLeap,
+                ("all_leap", "366_day"): cftime.DatetimeAllLeap,
+                ("julian",): cftime.DatetimeJulian,
+            }
+        )
+
     if isinstance(arg, str):
         (year, month, day, hour, minute, second, microsecond) = st2elements(
             arg
@@ -161,11 +173,6 @@ def dt(
     else:
         year = arg
 
-    #    calendar=_calendar_map.get(calendar, calendar)
-    #
-    #    return cftime.datetime(year, month, day, hour, minute, second,
-    #                           microsecond, calendar=calendar)
-
     for calendars, datetime_cls in _datetime_object.items():
         if calendar in calendars:
             return datetime_cls(
@@ -354,6 +361,8 @@ def st2datetime(date_string, calendar=None):
         `cftime.datetime`
 
     """
+    import cftime
+
     if date_string.count("-") != 2:
         raise ValueError(
             "Input date-time string must contain at least a year, a month "
@@ -388,6 +397,8 @@ def st2elements(date_string):
         `tuple`
 
     """
+    import cftime
+
     if date_string.count("-") != 2:
         raise ValueError(
             "Input date-time string must contain at least a year, a month "
@@ -450,6 +461,8 @@ def rt2dt(array, units_in, units_out=None, dummy1=None):
         # mask
         return np.ma.masked_all((), dtype=object)
 
+    import cftime
+
     units = units_in.units
     calendar = getattr(units_in, "calendar", "standard")
 
@@ -510,6 +523,8 @@ def dt2rt(array, units_in, units_out, dummy1=None):
     [-- 685.5]
 
     """
+    import cftime
+
     isscalar = not np.ndim(array)
 
     array = cftime.date2num(
@@ -545,8 +560,9 @@ def st2rt(array, units_in, units_out, dummy1=None):
             An array of floats with the same shape as *array*.
 
     """
+    import cftime
+
     array = st2dt(array, units_in)
-    #    array = units_out._utime.date2num(array)
     array = cftime.date2num(
         array, units=units_out.units, calendar=units_out._utime.calendar
     )

cf/data/collapse/collapse_active.py

@@ -1,22 +1,14 @@
-import datetime
 import logging
-import time
 from functools import wraps
 from numbers import Integral
 
-from ...functions import (
+from cf.functions import (
     active_storage,
     active_storage_max_requests,
     active_storage_url,
     is_log_level_info,
 )
 
-# try:
-#    from activestorage import Active
-# except ModuleNotFoundError:
-#    pass
-
-
 logger = logging.getLogger(__name__)
 
 # --------------------------------------------------------------------
@@ -185,6 +177,12 @@ def active_chunk_function(method, *args, **kwargs):
     # reason, then this will trigger (inside `actify`) a local
     # reduction being carried out instead.
     # ----------------------------------------------------------------
+    import datetime
+    import time
+
+    # Note: We know that the optional `activestorage` pacakge exists
+    #       because this was checked when active storage was enabled
+    #       with `cf.active_storage(True)`
     from activestorage import Active
 
     filename = x.get_filename()

cf/data/dask_utils.py

@@ -13,8 +13,6 @@
 from ..cfdatetime import dt, dt2rt, rt2dt
 from ..units import Units
 
-# from scipy.ndimage import convolve1d
-
 
 def cf_contains(a, value):
     """Whether or not an array contains a value.

cf/data/data.py

@@ -5,7 +5,6 @@
 from operator import mul
 
 import cfdm
-import cftime
 import numpy as np
 from cfdm.data.dask_utils import cfdm_where
 from cfdm.data.utils import new_axis_identifier
@@ -2198,6 +2197,8 @@ def _binary_operation(cls, data, other, method):
         # so that combination with cf.Query objects works.
         # ------------------------------------------------------------
         if not isinstance(other, cls):
+            import cftime
+
             if (
                 isinstance(other, cftime.datetime)
                 and other.calendar == ""

cf/field.py

@@ -9949,12 +9949,12 @@ def convolution_filter(
                   An unweighted 5-point moving average can be computed
                   with ``window=[0.2, 0.2, 0.2, 0.2, 0.2]``
 
-                Note that the `scipy.signal.windows` package has suite
-                of window functions for creating window weights for
-                filtering (see the examples for details).
+                .. note:: The `scipy.signal.windows` package has a
+                          suite of window functions for creating
+                          window weights for filtering (see the
+                          examples for details).
 
-                .. versionadded:: 3.3.0 (replaces the old weights
-                                  parameter)
+                .. versionadded:: 3.3.0
 
             axis:
                 Select the domain axis over which the filter is to be

cf/functions.py

@@ -7,6 +7,7 @@
 import warnings
 from collections.abc import Iterable
 from functools import partial
+from importlib.util import find_spec
 from itertools import product
 from math import isnan
 from os import mkdir
@@ -19,9 +20,7 @@
 from urllib.parse import urljoin, urlparse
 
 import cfdm
-import netCDF4
 import numpy as np
-from psutil import virtual_memory
 
 from . import __file__, __version__
 from .constants import OperandBoundsCombination, _stash2standard_name
@@ -150,6 +149,8 @@ def _free_memory():
         96496240.0
 
         """
+        from psutil import virtual_memory
+
         return float(virtual_memory().available)
 
 
@@ -1189,18 +1190,15 @@ def _parse(cls, arg):
                 insertion into the `_constants` dictionary.
 
         """
-        try:
-            import activestorage  # noqa: F401
-        except ModuleNotFoundError as error:
-            if arg:
-                error.msg += (
-                    ". Install the 'activestorage' package "
-                    "(https://pypi.org/project/PyActiveStorage) to enable "
-                    "active storage reductions"
-                )
-                raise
+        arg = bool(arg)
+        if arg and not find_spec("activestorage"):
+            raise ModuleNotFoundError(
+                "Must install the 'activestorage' package "
+                "(https://pypi.org/project/PyActiveStorage) to enable "
+                "active storage reductions"
+            )
 
-        return bool(arg)
+        return arg
 
 
 class active_storage_url(ConstantAccess):
@@ -1488,6 +1486,8 @@ def min_total_memory():
 
 def total_memory():
     """The total amount of physical memory (in bytes)."""
+    from psutil import virtual_memory
+
     return float(virtual_memory().total)
 
 
@@ -3275,6 +3275,8 @@ def default_netCDF_fillvals():
      'f8': 9.969209968386869e+36}
 
     """
+    import netCDF4
+
     return netCDF4.default_fillvals
 
 

cf/mixin/coordinate.py

@@ -1,5 +1,3 @@
-# from itertools import chain
-
 from ..data.data import Data
 from ..decorators import (
     _deprecated_kwarg_check,

cf/mixin/fielddomain.py

@@ -726,9 +726,9 @@ def _indices(self, config, data_axes, ancillary_mask, kwargs):
                                     for i, p in zip(identities, points)
                                 ]
                             )
-                            raise ImportError(
-                                "Must install matplotlib to create indices "
-                                f"for {self!r} from: {x}"
+                            raise ModuleNotFoundError(
+                                "Must install the 'matplotlib' package to "
+                                f"create indices for {self!r} from: {x}"
                             )
 
                         def _point_not_in_cell(nodes_x, nodes_y, point):

cf/read_write/um/umread.py

@@ -5,11 +5,9 @@
 from uuid import uuid4
 
 import cfdm
-import cftime
 import numpy as np
 from cfdm import Constructs, is_log_level_info
 from cfdm.read_write.exceptions import DatasetTypeError
-from netCDF4 import date2num as netCDF4_date2num
 
 from cf import __Conventions__, __version__
 from cf.constants import _stash2standard_name
@@ -1866,6 +1864,8 @@ def coord_positive(self, c, axiscode, domain_axis_key):
     def ctime(self, rec):
         """Return elapsed time since the clock time of the given
         record."""
+        import cftime
+
         reftime = self.refUnits
         LBVTIME = tuple(self.header_vtime(rec))
         LBDTIME = tuple(self.header_dtime(rec))
@@ -2287,13 +2287,17 @@ def dtime(self, rec):
         key = (LBDTIME, units, calendar)
         time = _cached_date2num.get(key, None)
         if time is None:
+            from netCDF4 import date2num as netCDF4_date2num
+
             # It is important to use the same time_units as vtime
             try:
                 if self.calendar == "gregorian":
                     time = netCDF4_date2num(
                         datetime(*LBDTIME), units, calendar
                     )
                 else:
+                    import cftime
+
                     time = netCDF4_date2num(
                         cftime.datetime(*LBDTIME, calendar=self.calendar),
                         units,
@@ -2949,6 +2953,8 @@ def vtime(self, rec):
 
         time = _cached_date2num.get(key, None)
         if time is None:
+            import cftime
+
             # It is important to use the same time_units as dtime
             try:
                 time = cftime.date2num(

cf/regrid/regrid.py

@@ -1904,9 +1904,9 @@ def esmpy_initialise():
     """
     try:
         import esmpy
-    except ImportError:
-        raise RuntimeError(
-            "Regridding will not work unless the esmpy library is installed"
+    except ModuleNotFoundError:
+        raise ModuleNotFoundError(
+            "Must install the 'esmpy' package to enable regridding"
         )
 
     # Update the global 'esmpy_methods' dictionary